Questions tagged [gravitational-waves]

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Gravitational brehmsstralung

I have read this pdf, and its 5th paragraph, where it talks about gravitational brehmsstralung. https://www.researchgate.net/publication/243311274_Gravitons_in_Minkowski_space-...
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Are we closer to a theory of everything thanks to the detection of gravitational waves?

A couple of weeks ago I heard an astronomer explain that one of the latest detections of gravitational waves was accompanied by simultaneous detections of the same astronomical event in various other ...
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Does a graviton in vacuum have a rest frame?

I have read these questions: Does a photon in vacuum have a rest frame? Based on dmckee's answer, the answer is no to a photon's rest frame. In the modern view each particle has one and only one ...
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Are Gravitrons still hypothetical? [duplicate]

With the dectection of gravitational waves, can it be assumed that gravity works in the same way as the other fields? If so, isn’t the gravitron a proven part of QFT? Because the wikipedia page says ...
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Do gravitational waves lose energy through interaction with i.e. matter or magnetic fields? [duplicate]

Gravitational waves dilute while traversing space like any other radiation, and their amplitudes are proportional to r-2, that's a basic. But do they lose energy while traversing through matter or ...
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The June 23 issue of New Scientist says gravitational waves twist when they travel, and do so counterclockwise. Why?

Also, the same article then says that if gravitational waves ever did move in a clockwise fashion, it means the black holes slammed into each other much more rapidly. Huh?
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If we could only see gravitational waves, how “bright” would the sky be?

I feel like we actually are not sure about the answer (as there have not been many detections so far, so our knowledge about gravitational waves is probably not very deep), so this might be too ...
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Does heat radiation also produce gravitational waves?

My question is as it sounds. We know that in a vacuum, materials radiate away their heat energy. To my understanding, this is the result of charged particles losing their energy to produce photons. ...
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Factor of 4 (or 2) in the gravitoelectromagnetic (GEM) Lorentz-force law. Which is correct? Why is it there?

I realize that the Gravitoelectromagnetic equations (GEM) are derived from the Einstein field equation (EFE) in the degenerate case of reasonably flat spacetime, which is the case for the propagation ...
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Can gravitational waves be emitted from single neutron stars?

I wonder whether GWs can be produced and emitted by single neutron stars, since it is known that typically they must be emitted by a binary system of them. If so, can the source be an isolated cool ...
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Does Earth emit Gravitational waves?

We know about bohrs model and his vagaue postulate challenging Rutherford for discrete orbits and not emitting electromagnetic waves during this. Extending this idea to our solar system, does earth ...
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What are the wave characteristics for the detected gravitational wave?

I'm curious to know what the amplitude and wavelength of the detected gravitational waves are? The paper mentions some characteristics of the detection event, but not what that means for the wave ...
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How are the 4 km arms of LIGO measured so accurately?

The arms of the LIGO interferometer are 4 km long. Now, LIGO functions by measuring phase difference between two beams of light coming (as in a Michelson interferometer) to a sensitivity of $10^{-18}\:...
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Slowdown of gravitational waves measurement

As far as I can understand, the gravitational waves also slow down on interaction with matter similar to light rays. I am trying to understand if we can measure this? Suppose we put two detectors on ...
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Do stars amplify or refract gravitational waves?

I am curious if stars (or other massive bodies) amplify or refract gravitational waves in a manner similar to the following. Amplification In the case of amplification, do massive bodies affect ...
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Are gravitational waves the slowest waves known to science?

Consider that two celestial bodies orbit have a frequency of one rotation every 50,000 years, it means that the periodicity of the gravitational wave sensed by a distant observer is about 50k years. ...
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Is the signal detected by LIGO a result of the merging of the horizons or the singularities?

Regarding gravity waves, some YouTube videos show simulations of the gravity waves detected by LIGO in August of 2017. Is the "chirp" the result of the merger of the event horizon or the merger of ...
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Are the LIGO observations proof of a black hole merger, and what happened to the black holes?

Recent reports claim that the gravitational waves detected by LIGO match up with the signal expected from two black holes merging as predicted by general relativity. Additionally, the masses of both ...
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How are black hole masses calculated from gravitational waves? [duplicate]

I would like to know what data is used from gravitational wave detections to calculate black hole masses and how. Also, what else can you deduce from gravitational wave detections? What was the exact ...
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Quantum gravity and inspirals by emission of gravitational waves [closed]

Should we expect that quantum gravity, just as quantum theory forbids the decay of the fundamental level, avoids the collision of gravitationally bound systems at small scales, despite they emit ...
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Approximating a linearized gravitational wave expression

This is in the context of gauge fixing condition for obtaining linearized gravitational waves. $g_{ab}=\eta_{ab}+h_{ab}$ and $h_{ab}$ is the small perturbation that stands for the gravitational wave. ...
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Is there a “magnetic gravitational” field? [duplicate]

Electromagnetic waves, in the classical sense, are due to oscillations in two different fields. They propagate at the speed of light, and they can be described by a set of differential equations. ...
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Do non-uniformly rotating axially symmetric bodies emit gravitational waves?

In the first reply to this question it is written that: There is no gravitational waves for a uniformly rotating axially symmetric body, because the metric doesn't depend on time.[..] The ...
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How does LIGO detect Gravitational Waves if they bend both space and time?

Please note that this is not an inquiry into the mechanisms of technology that LIGO uses to detect gravitational waves. Also, I am not a flat-earther. I was watching physicists vs. flat-earthers ...
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Pendulum usage in gravitational wave detectors

I've read that pendulums are (or were) used to calibrate the distance between the mirrors in a gravitational wave detector. In principle pendulums are supposed to be moving in just one plane no matter ...
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Has anyone ever tried to derive gravitoelectromagnetic waves equation?

Has anyone ever tried to derive gravitoelectromagnetic waves equation? As we know, there is Maxwell-like equation in gravity. Has anyone here ever formulated gravito electromagnetic waves equation ...
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Determine expansion rate of universe from gravitational waves LIGO?

I heard on the TED Radio Hour that the LIGO team was able to make an independent measurement of the Hubble constant and the increasing expansion rate of the universe when they detected the ...
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Gravitational wave equations? [closed]

I am looking for a set of equations, one to calculate GW amplitude in watts and one to calculate frequency... I believe I have located the correct frequency equation yet I cannot find a source for ...
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Could LIGO detect two simultaneous gravitational waves?

Hypothetically if two (or more) gravitational waves were passing through the LIGO detector at the same instant, can the LIGO team deduce from the data that there were two simultaneous waves passing? ...
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What does it mean by $h_{\mu\nu}$ having “gauge symmetry”?

$$\partial^\rho \partial_\rho h_{\mu\nu} - \partial_\mu \partial^\rho h_{\rho\nu} - \partial_\nu \partial^\rho h_{\rho\mu} + \partial_\mu \partial_\nu {h^\rho}_\rho = 0$$ Here $h_{\mu\nu}$ is a ...
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Is there a “CGBR”?

The recent discovery by the LIGO made me wonder about this. We know that there exists a CMBR, Cosmic Microwave Background Radiation, a blanket of electromagnetic energy covering the universe, made by ...
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Are gravitons bound by the event horizon? [duplicate]

I understand that photons, even when traveling at the speed of light, cannot escape the event horizon of a black hole. Are gravitons and other virtual particles traveling at the speed of light also ...
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Gravitational waves and Possible distortions in time?

Straight off, i know similar questions have been asked at How close would you have to be to the merger of two black holes, for the effects of gravitational waves to be detected without instruments? ...
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Formula to calculate the frequency of gravitational waves emitted by two bodies inspiral?

Is there a small straightforward equation which can give the approximate frequency of the gravitational waves emitted by the inspiral of two bodies?
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Visualising Gravitational waves

I'm studying General relativity, and I want to clarify the qualitative nature of how gravitational waves propagate. Simple is best, so I want to imagine a single binary black hole system orbiting in ...
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Red-shifting due to emitting gravitational waves

Light waves exert their own gravitational pull and must be emitting gravitational waves, losing energy in the process. Does this mean that light becomes red-shifted as it travels even without the ...
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What is the relationship between a gravitational wave and a graviton? [duplicate]

Gravitational waves were theorized a century ago and recently discovered, leading to the awarding of the 2017 Nobel Prize in Physics. According to Wikipedia: Gravitational waves transport energy as ...
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If light was 2 parts per trillion slower than gravitational waves, would we know this from Gauss' law? [duplicate]

In the recent neutron star merger. The gravitational waves started 100 seconds before the collision, which is when they reached a max and STOPPED. The mass quadrupole had stopped changing, which means ...
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How do the LIGO facilities know that their gravitational waves have not been distorted by other events and other waves?

Several black hole collisions have been detected. How do they determine if the gravitational waves have been strengthened or weakened by interaction with other event waves?
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Proper time elapsed along a worldline

The question is about the following metric describing the gravitational wave propagating along the $z$ direction: $$ds^2=-dt^2+(1+h(t,z))dx^2+(1-h(t,z))dy^2+dz^2$$ where $$h(t,z)=H\cos{k}(t-z).$$ $...
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Effective stress-energy tensor for a gravitational wave, compared to static semi-Newtonian case

There is a calculation that I had been thinking for a long time of working out to my own satisfaction, both because of its intrinsic importance and because it seemed like it would be fun. This was to ...
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Is Gravity Cumulative

This is to tie in with a previous question >The Sun's Orbit - Is it What We Think? Are gravitational waves cumulative? and if so how does this affect our galaxy and other astronomical bodies? Now ...
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Why gravitational waves are not part of thermal phenomena?

Electromagnetic waves are part of thermal phenomena in the form of thermal radiations. But why gravitational waves do not show up as a thermal phenomenon, for example, why gravitational waves do not (...
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Do gravitational waves diminish over time/distance?

Just wondered how they compare to sound waves, naturally they travel at the speed of light, but I was wondering if they diminish over time like sounds waves. Cheers.
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Will gravitational wave detectors be able to locate black hole collisions in time to view them?

Can a single LIGO identify the general direction of a black hole collision? Could multiple observatories be able to accurately pinpoint the direction from them so that telescopes could quickly point ...
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Dark matter and LIGO

In addition to the functioning LIGO detectors (two in USA and one in Italy), I am aware there are some gravitation wave detectors under construction. More detectors should provide more statistical ...
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How well can we localize gravitational wave sources?

A recent question cited a story about the recent gravitational wave detection saying that we can use the gravitational wave sensing to find supernova earlier in their process of collapse: [with the ...
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Why do detectors for gravitational waves have only two perpendicular arms, not three?

I wonder why detectors for gravitational waves have only two perpendicular arms, not three. Having three arms appears to allow for better detection of direction, or may even increase sensitivity (I ...
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Is it possible that the LIGO results are anomalies? [duplicate]

Since it was reported recently that the supermassive black holes at the centres of galaxies may in fact be as many as 20,000 smaller black holes I wondered if, if these black holes collide with one ...
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About the “Spindown problem”

I am studying General Relativity, following the lessons too, and some days ago the professor mentioned, in a very "fancy and quick" way a thing called "the spindown problems". For what I understood, ...